import { useState, useEffect } from 'react'
import { useAuth } from '../context/AuthContext'
import { Icon, getActivityIconName } from '../components/Icons'
import Logo from '../components/Logo'

const API_URL = '/api'

// Coach greetings based on context
const getCoachGreeting = (user, todayWorkout) => {
  const hour = new Date().getHours()
  const name = user?.name?.split(' ')[0] || 'du'

  if (todayWorkout) {
    // There's a workout today
    if (hour < 10) {
      return `Godmorgon ${name}! Idag kör vi ${todayWorkout.name.toLowerCase()}. Redo?`
    } else if (hour < 14) {
      return `${todayWorkout.name} står på schemat idag. Dags att köra!`
    } else if (hour < 18) {
      return `Eftermiddagspass? ${todayWorkout.name} väntar på dig.`
    } else {
      return `Kvällspass ${name}? ${todayWorkout.name} – perfekt för att avsluta dagen.`
    }
  } else {
    // Rest day
    if (hour < 10) {
      return `Godmorgon ${name}! Vilodag idag – perfekt för återhämtning.`
    } else if (hour < 14) {
      return `Ingen träning schemalagd. Ta en promenad eller stretcha lite?`
    } else if (hour < 18) {
      return `Vila är också träning! Lätt rörelse eller mobilitet idag?`
    } else {
      return `Lugn kväll ${name}. Ladda batterierna till nästa pass!`
    }
  }
}

// Rest day tips
const restDayTips = [
  { iconName: 'walking', text: 'Promenad' },
  { iconName: 'yoga', text: 'Stretching' },
  { iconName: 'swimming', text: 'Simning' },
  { iconName: 'cycling', text: 'Cykling' },
]

// Get weekday names
const weekdays = ['Mån', 'Tis', 'Ons', 'Tor', 'Fre', 'Lör', 'Sön']

function Dashboard({ onStartWorkout, onNavigate }) {
  const { user, logout } = useAuth()
  const [program, setProgram] = useState(null)
  const [todayWorkout, setTodayWorkout] = useState(null)
  const [loading, setLoading] = useState(true)
  const [currentWeekStart, setCurrentWeekStart] = useState(getWeekStart(new Date()))

  useEffect(() => {
    fetchData()
  }, [])

  const fetchData = async () => {
    try {
      const res = await fetch(`${API_URL}/programs/1`)
      const data = await res.json()
      setProgram(data)
      
      // Determine today's workout based on day of week
      const dayOfWeek = new Date().getDay()
      const adjustedDay = dayOfWeek === 0 ? 7 : dayOfWeek
      const todayDay = data.days?.find(d => d.day_number === adjustedDay)
      setTodayWorkout(todayDay || null)
      
      setLoading(false)
    } catch (err) {
      console.error('Failed to fetch data:', err)
      setLoading(false)
    }
  }

  if (loading) {
    return (
      <div className="dashboard loading">
        <div className="spinner"></div>
        <p>Laddar...</p>
      </div>
    )
  }

  const workoutDays = program?.days?.map(d => d.day_number) || []

  return (
    <div className="dashboard">
      <header className="dashboard-header">
        <div className="header-top">
          <h1 className="brand-title">
            <Logo />
            <span className="brand-name">Gravl</span>
          </h1>
          <nav className="nav-menu">
            <button className="nav-btn active"><Icon name="home" size={18} /></button>
            <button className="nav-btn" onClick={() => onNavigate('progress')}><Icon name="chart" size={18} /></button>
            <button className="nav-btn" onClick={() => onNavigate('encyclopedia')} title="Exercise Encyclopedia"><Icon name="search" size={18} /></button>
            <button className="nav-btn" onClick={() => onNavigate('profile')}><Icon name="user" size={18} /></button>
            <button className="nav-btn logout" onClick={logout}><Icon name="logout" size={18} /></button>
          </nav>
        </div>
      </header>

      <main className="dashboard-main">
        {/* Week Calendar - TOP */}
        <section className="week-calendar">
          <div className="calendar-header">
            <button
              className="calendar-nav"
              onClick={() => setCurrentWeekStart(addDays(currentWeekStart, -7))}
            >
              <Icon name="chevronLeft" size={16} />
            </button>
            <span className="calendar-title">
              {formatWeekRange(currentWeekStart)}
            </span>
            <button
              className="calendar-nav"
              onClick={() => setCurrentWeekStart(addDays(currentWeekStart, 7))}
            >
              <Icon name="chevronRight" size={16} />
            </button>
          </div>
          <div className="calendar-days">
            {weekdays.map((name, idx) => {
              const date = addDays(currentWeekStart, idx)
              const dayNum = idx + 1
              const isToday = isSameDay(date, new Date())
              const hasWorkout = workoutDays.includes(dayNum)
              const workout = program?.days?.find(d => d.day_number === dayNum)
              
              return (
                <div
                  key={idx}
                  className={`calendar-day ${isToday ? 'today' : ''} ${hasWorkout ? 'has-workout' : ''}`}
                  onClick={() => hasWorkout && workout && onStartWorkout(workout)}
                >
                  <span className="day-name">{name}</span>
                  <span className="day-date">{date.getDate()}</span>
                  {hasWorkout && <span className="day-dot" />}
                </div>
              )
            })}
          </div>
        </section>

        {/* Coach Section with Today's Action */}
        <section className="coach-section">
          <div className="coach-greeting">
            <div className="coach-avatar">
              <Icon name="coach" size={36} />
            </div>
            <div className="coach-message">
              <p>{getCoachGreeting(user, todayWorkout)}</p>
            </div>
          </div>

          {/* Today's Action */}
          <div className="today-action">
            {todayWorkout ? (
              // Workout today - show workout card
              <div className="today-workout-card" onClick={() => onStartWorkout(todayWorkout)}>
                <div className="workout-info">
                  <h3>{todayWorkout.name}</h3>
                  <span className="workout-meta">
                    {todayWorkout.exercises?.filter(e => e.name).length} övningar • ~45 min
                  </span>
                </div>
                <div className="workout-action">
                  <Icon name="arrowRight" size={24} />
                </div>
              </div>
            ) : (
              // Rest day - show tips + add button
              <div className="rest-day-section">
                <div className="rest-tips">
                  {restDayTips.map((tip, i) => (
                    <span key={i} className="tip-badge">
                      <Icon name={tip.iconName} size={16} />
                      {tip.text}
                    </span>
                  ))}
                </div>
                <button
                  className="add-workout-btn"
                  onClick={() => onNavigate('select-workout')}
                >
                  <Icon name="plus" size={20} />
                  <span>Lägg till pass</span>
                </button>
              </div>
            )}
          </div>
        </section>

        {/* Quick Stats */}
        <section className="quick-stats">
          <div className="stat-card">
            <span className="stat-value">{workoutDays.length}</span>
            <span className="stat-label">Pass/vecka</span>
          </div>
          <div className="stat-card">
            <span className="stat-value">2</span>
            <span className="stat-label">Denna vecka</span>
          </div>
          <div className="stat-card">
            <span className="stat-value stat-icon"><Icon name="fire" size={28} /></span>
            <span className="stat-label">Streak: 5</span>
          </div>
        </section>
      </main>
    </div>
  )
}

// Helper functions
function getWeekStart(date) {
  const d = new Date(date)
  const day = d.getDay()
  const diff = d.getDate() - day + (day === 0 ? -6 : 1)
  return new Date(d.setDate(diff))
}

function addDays(date, days) {
  const d = new Date(date)
  d.setDate(d.getDate() + days)
  return d
}

function isSameDay(d1, d2) {
  return d1.getDate() === d2.getDate() && 
         d1.getMonth() === d2.getMonth() && 
         d1.getFullYear() === d2.getFullYear()
}

function formatWeekRange(weekStart) {
  const end = addDays(weekStart, 6)
  const startMonth = weekStart.toLocaleDateString('sv-SE', { month: 'short' })
  const endMonth = end.toLocaleDateString('sv-SE', { month: 'short' })
  
  if (startMonth === endMonth) {
    return `${weekStart.getDate()} - ${end.getDate()} ${startMonth}`
  }
  return `${weekStart.getDate()} ${startMonth} - ${end.getDate()} ${endMonth}`
}

export default Dashboard